This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPP third generation partnership project
ADSL asymmetric digital subscriber line
AP access point (base station)
BS base station
BW bandwidth
DL downlink (as an example an AP towards a UE)
eNB EUTRAN Node B (evolved Node B)
EPC evolved packet core
EUTRAN evolved UTRAN (LTE)
FDD frequency division duplex
FSU flexible spectrum use
LTE long term evolution
MAC medium access control
MM/MME mobility management/mobility management entity
MS mobile station
OFDMA orthogonal frequency division multiple access
PDCP packet data convergence protocol
PDU protocol data unit
PHY physical
RACH random access channel
RB resource block
RLC radio link control
RRC radio resource control
SGW serving gateway
TDD time division duplex
UE user equipment
UT user terminal
UL uplink (as example a UE towards an AP)
UTRAN universal terrestrial radio access network
The specification of a communication system known as evolved UTRAN (EUTRAN, also referred to as UTRAN LTE or as EUTRA) has been considered within the 3GPP. As specified the DL access technique is OFDMA, and the UL access technique is SC-FDMA (single carrier, frequency division multiple access).
One specification of interest in this regard is 3GPP TS 36.300, V8.5.0 (2008 May), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8), which is incorporated by reference herein in its entirety. This system may be referred to for convenience as LTE Rel-8, or simply as Rel-8. Note that this is a stage 2 specification, and may not exactly describe the system as currently implemented. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the entire Release 8 LTE system.
Of particular interest herein are the discussions of 3GPP LTE which have been targeted towards IMT-A systems, referred to herein for convenience simply as LTE-Advanced (LTE-A). Of additional interest herein are local area (LA) deployment scenarios using a scalable bandwidth (of up to, for example, 100 MHz) with flexible spectrum use (FSU). This system concept may be referred to herein for convenience as LTE-A.
FSU generally refers to any spatially and/or temporally varying use of radio spectrum/radio resources. As a non-limiting example, FSU enables networks of different operators to operate on a same radio spectrum (using the same shared radio resources). FSU allows a plurality of operators to collectively utilize a frequency band such that there are no dedicated portions licensed to a single operator. The frequency band may still be licensed, however regulatory rules will dictate how bandwidth sharing is executed. This allows each operator to adjust its frequency use according to local needs such that the scarce spectrum is more efficiently utilized than in non-FSU models (e.g., the current regulation model). FSU may also be applied on an unlicensed band, though the flexible spectrum use would still have to be regulated so that the networks can reliably operate.
FSU creates a framework for a flexible and dynamic use of radio resources for enabling network operators to have access to the resources. A goal is to utilize the spectrum in an as optimal way as possible in order to achieve a high use flexibility of the radio resources, such as radio frequencies.
The FSU concept for Release 10 of LTE may have been considered a distributed FSU scheme, i.e., there may be no FSU server to control the resource assignments. One important concept of distributed FSU is local awareness, the goal of which is to gain an understanding of spectrum situation/opportunities in a region (neighbourhood), in order to self-organize flexible spectrum use. Local awareness can include information of neighbouring nodes, including possibly their future intentions.
In FSU it can be expected that several APs (and UEs) can use the same shared radio resource pool. If the neighbouring APs are far from each other this can be readily accomplished as interference issues do not arise. However, in a realistic setting the neighbouring APs can be located close to one another so that interference issues do arise. It may be the case that one of the involved APs needs to make room for another AP, and either completely relinquish some shared resources or at least reduce its transmission power on those resources.
A problem that arises in this context is how to settle these situations and decide (in a fair manner) which of the APs has the right to use the shared radio resources in question. Another question is how to best indicate to the other AP the intention of the AP to begin using a radio resource that the AP has reserved.
In LTE, radio resource management is arranged within a single network and utilizes the X2 interface between base stations (eNBs). Reference in this regard may be made to FIG. 1, which reproduces FIG. 4.1 of 3GPP TS 36.300, and shows the overall architecture of the EUTRAN (LTE) system. The EUTRAN system includes eNBs that provide the EUTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of the above-mentioned X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME (Mobility Management Entity) by means of a S1 MME interface and to a Serving Gateway (SGW) by means of a S1 interface. The S1 interface supports a many to many relationship between MMEs/Serving Gateways and eNBs.
However, the inter-access point interface does not exist when cells belong to different networks, or are based on an ADSL backbone (femto BS).
The exemplary embodiments of the invention relate to how to most efficiently and fairly use an FSU wireless communication system. In addition, the exemplary embodiments of the invention relate to control signalling that is an element of an efficient FSU implementation.